High activity oxide Pr0.3Sr0.7Ti0.3Fe0.7O3−δ as cathode of SOEC for direct high-temperature steam electrolysis

A high activity ferrite Pr_0.3Sr_0.7Ti_0.3Fe_0.7O_3?δ (PSTF) has been synthesized and examined as a cathode of solid oxide electrolysis cell (SOEC) for direct high-temperature steam electrolysis. The SOEC with a configuration of PSTF|YSZ|LSM-YSZ was operated under H₂O concentrations ranging from 20%H₂O/Ar to 60%H₂O/Ar and exhibited excellent electrochemical performances. Polarization resistance of the electrolyzer was as small as 0.43 Ω cm² in 60%H₂O/Ar at 1.85 V at 800 °C. According to AC impendence spectra analyzing, gas diffusion process was the rate-determine-step (RDS) under smaller current density, while under larger current density, transport properties in the electrodes and the interfaces of electrode/electrolyte was RDS. The electrochemical properties of PSTF cathodes were systematically investigated and compared when they were exposed to gas atmosphere with and without safe gas (H₂). The obtained results demonstrated that PSTF electrode could conceivably avoid any hydrogen feeding for steam electrolysis.     

Thermal simulation of large-scale lithium secondary batteries using a graphite–coke hybrid carbon negative electrode and LiNi0.7Co0.3O2 positive electrode

Thermal simulation was applied to 2 Wh-class cells (diameter 14.2 mm, height 50 mm) using LiNi_0.7Co_0.3O₂ or LiCoO₂ as the positive electrode material, in order to clarify the thermal behavior of the cells during charge and discharge. The thermal simulation results for the 2 Wh-class cells showed a good agreement with measured temperature values. The heat generation of a cell using LiNi_0.7Co_0.3O₂ was found to be much less than that using LiCoO₂ during discharge. This difference was considered to be caused by the difference in the change of entropy. A 250 Wh-class cell (diameter 64 mm, height 296 mm) was also constructed using LiNi_0.7Co_0.3O₂ and thermal simulation was applied. We confirmed that the results of the thermal simulation agreed with measured values and that this simulation model is effective for analyzing the thermal behavior of large-scale lithium secondary batteries.     

DZL2—0.7型锅炉加装过热器的探讨

目前有些小型的塑料、乳品、化工等工厂,按实际生产工艺要求,需使用温度为300℃的蒸汽,而这些小型工厂所用的锅炉多数为DZL型蒸汽锅炉,其蒸发量在2～10t/h,工作压力为0.7～1.6MPa,锅炉生产饱和蒸汽的温度为170～200℃,难以满足生产用汽的需要,若要更换锅炉,又有资金上的困难。因此,就提出了在现有的DZL型蒸汽锅炉上加装过热器的改造问题。     

KZL2-0.7型锅炉加装过热器的节能效果

本文对 KZL2-0.7型锅炉加装过热器的改造方法作了详细的分析,并对改造后锅炉的节能效果作了探讨。     

Cobalt-free Sr0.7Y0.3CuO2+δ as a cathode for intermediate-temperature solid oxide fuel cell

Cobalt-free oxide Sr_0.7Y_0.3CuO_2+δ (SYCu) with one-dimensional structure has been investigated as potential cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. The crystal structure, chemical compatibility, thermal expansion and electrochemical performance were examined by X-ray diffraction technique, electrochemical workstation and thermal dilatometer. One-dimensional structure Sr_1−xY_xCuO_2+δ and Sr_2−xY_xCuO_3+δ phases appeared as the main parts after calcination above 900 °C. The copper based oxide SYCu showed a thermal expansion coefficient (TEC) about 11.1 × 10⁻⁶/°C at 25–800 °C, exhibiting good physical compatibility with samarium doped cerium (SDC) electrolyte. High electro-catalytic performance was obtained for SYCu cathode in a symmetrical cell with a polarization resistance (R_p) of 0.029 Ω cm² and an overpotential of 4.9 mV at 100 mA/cm² at 800 °C, showing great promising use as cathode materials for IT-SOFCs. In addition, the polarization resistance of SYCu cathode remain constant after operation at 800 °C for 100 h, showing excellent long-term stability at operation temperature.     

La1−xSrxFe0.7Ni0.3O3−δ as both cathode and anode materials for Solid Oxide Fuel Cells

La_1?xSr_xFe_0.7Ni_0.3O_3?δ (x = 0, 0.1 and 0.2, LSFNx) are investigated as both cathode and anode materials for Solid Oxide Fuel Cells (SOFCs). The structure, microstructure and electrochemical properties of these materials are studied under oxidizing and reducing atmospheres. In air, the electrodes exhibit polarization resistance of 0.1 Ωcm² at 800 °C under open circuit voltage. In a H₂ atmosphere, Ni nanoparticles are exsolved on the surface, leading to a polarization resistance as low as 0.06 Ωcm². A cell with a 350 μm thick La_0.9Sr_0.1Ga_0.8Mg_0.2O_3?δ electrolyte and LSFN electrodes generates a power output of 540 mWcm^?2 at 800 °C. Moreover, stable values of power density are obtained after successive oxidation/reduction cycles, confirming the reversibility of the electrodes.     

Ni-doped A-site-deficient La0.7Sr0.3Cr0.5Mn0.5O3-δ perovskite as anode of direct carbon solid oxide fuel cells

A Ni-doped A-site-deficient La_0.7Sr_0.3Cr_0.5Mn_0.5O_3-δ perovskite (N-LSCM) was synthesized and systematically characterized towards the application as the anode electrode for direct carbon solid oxide fuel cells (DC-SOFCs). The microstructure and electrochemical properties of N-LSCM under the operation conditions of DC-SOFCs have been evaluated. An in-situ exsolution of Ni nanoparticles on the N-LSCM perovskite matrix is found, revealing a maximum power density of 153 mW cm⁻² for the corresponding DC-SOFC at 850 °C, compared to 114 mW cm⁻² of the cell with stoichiometric LSCM. The introduction of Ni nanoparticles exsolution and A-site deficient is believed to boost the formation of highly mobile oxygen vacancies and electrochemical catalytic activity, and further improves the output performance of the DC-SOFC. It thus promises as a suitable anode candidate for DC-SOFCs with whole-solid-state configuration.     

DZL0.7—0.7/95/70—AⅡ链条炉排热水锅炉的设计

1.前言 在我国中小容量的锅炉中,锅壳式卧式外燃型锅炉占了极大部分,有蒸汽锅炉,也有热水锅炉。由于该类锅炉的结构特点,其中热水锅炉在运行过程中,发生了后管板裂纹等严重威胁安全运行的缺陷。为此,劳动部在1991年发布的《热水锅炉安全技术监察规程》（以下简称《新规程》）第26条规定:“对于锅壳式卧式外燃锅炉,设计、制造单位必须采取技术措施,解决管板裂纹或泄漏及锅壳鼓包等问题”。对于上述问题,我们厂做了一定的试验研究工作。早在1984年,我厂就与上海机械学院合作,进行了锅壳式卧式外燃热水锅炉水动力模化试验研究（以下简称《模化试验》）,并取得了满意的结果。该《模化试验》的成果获得了上海市第二轻工业局科技进步一等奖。根据《模化试验》的成果,我厂在1985年研制开发了DZL1.4—0.7/95/70一AⅡ链条炉排热水锅炉。在该锅炉的本体结构中,采用回水引射和低     

One-dimensional Sr0.7Y0.3CoO2.65−δ nanofibers as cathode material for IT-SOFCs

One dimensional (1-D) Sr_0.7Y_0.3CoO_2.65−δ (SYCO) nanofibers and nanofiber-based Sr_0.7Y_0.3CoO_2.65−δ-Gd_0.2Ce_0.8O_1.9 (SYCO-GDC) composites have been prepared and studied as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). 1-D SYCO nanofibers are synthesized by electrospinning technique and the subsequent calcination processes. X-ray diffraction (XRD) results indicate that 900 °C is adequate for the formation of phase pure SYCO, much lower than the temperatures adopted in other reported methods for SYCO synthesis. 1-D nanofiber-based SYCO-GDC composite cathodes have been fabricated by infiltrating the ionic conducting GDC phase into the porous SYCO nanofiber scaffolds, achieving interfacial polarization resistances of 0.651, 0.200, 0.057 and 0.011 Ω cm² at 600, 650, 700 and 750 °C, respectively, with an optimized SYCO:GDC mass ratio of 1:0.44. The stability of this SYCO-GDC (1:0.44) composite cathode was affirmed by 108-h constant current test. All these results suggest that 1-D nanofiber-based SYCO-GDC composite is a promising cathode material for IT-SOFCs.     

Performance of solid oxide fuel cells based on proton-conducting BaCe0.7In0.3-xYxO3-δ electrolyte

The performances of solid oxide fuel cells with proton conductors BaCe_0.7In_0.3−xY_xO_3−δ (BCIY, x = 0, 0.1, 0.2, 0.3) as electrolytes were investigated in this work. The cell based on BaCe_0.7In_0.2Y_0.1O_3−δ electrolyte showed maximum power outputs of 0.114, 0.204 and 0.269 Wcm⁻² at 600, 650 and 700 °C, respectively. After operating at a constant cell voltage output of 0.5V for 40h, no obvious degradation in performance was observed for the cells based on BaCe_0.7In_0.3O_3−δ and BaCe_0.7In_0.2Y_0.1O_3−δ electrolytes. However, although relatively lower resistances and higher initial power outputs were found for cells based on BaCe_0.7In_0.1Y_0.2O_3−δ and BaCe_0.7Y_0.3O_3−δ electrolytes, rapid cell performance degradations were observed for these two cells. The stability under cell operating conditions remained a challenge for cells using BaCe_0.7In_0.1Y_0.2O_3−δ and BaCe_0.7Y_0.3O_3−δ electrolytes.     

Microstructure, oxygen stoichiometry and electrical conductivity of flame-sprayed Sm0.7Sr0.3CoO3−δ

A SSC deposit has been prepared by flame spraying using Sm_0.7Sr_0.3CoO_3−δ (SSC) powder synthesized by a solid-state reaction. A post-spray annealing treatment of the SSC deposit has been performed. The coating characterization includes: the electrical conductivity of the SSC deposit along the lamellar direction measured by a four-electrode D.C. approach, the microstructures of SSC powders and deposits characterized using X-ray diffraction and scanning electron microscopy, the oxygen stoichiometry in both the as-sprayed and annealed deposits and starting powder determined by redox titration. The results show that a significant oxygen deficiency (12%) occurs in the sprayed powder particles during high temperature flame spraying, leading to reduction of the electrical conductivity of the as-sprayed SSC deposit. It is found that oxygen can be recovered through post-spray annealing treatment. After annealing at 900 °C for 5 h or at 1100 °C for 10 h, the electrical conductivity of annealed SSC reaches 433 S cm⁻¹ or 510 S cm⁻¹ at 600 °C due to a sharp recovery of deficient oxygen and microstructural change.     

The effect of Mn substitution for Ni on the structural and electrochemical properties of La0.7Mg0.3Ni2.55−xCo0.45Mnx hydrogen storage electrode alloys

The structures, hydrogen storage property and electrochemical properties of the $\text{La}{}_{0.7}\text{Mg}{}_{0.3}\text{Ni}{}_{\mathrm{2.55-x}}\text{Co}{}_{0.45}\text{Mn}{}_{\mathrm{x}}\text{(x=0.0,0.1,0.2,0.3,0.4,0.5)}$ electrode alloys has been studied systematically. It can be found that, by X-ray powder diffraction, the alloys are all consisted of the (La,Mg)Ni₃ phase and the LaNi₅ phase, and the lattice parameters and cell volumes of both the (La,Mg)Ni₃ phase and the LaNi₅ phase increase with increasing Mn content in alloys. The P–C isotherms curves indicate that the hydrogen storage capacity first increases and then decreases with increasing x, and the equilibrium pressure decreases. The electrochemical measurements show that the maximum discharge capacity increases from $\text{342.6}\text{(x=0.0)}$ to $\text{368.9}\text{mA}\text{h}\text{/}\text{g}\text{(x=0.3)}$ and then decreases to $\text{333.5}\text{mA}\text{h}\text{/}\text{g}\text{(x=0.5)}$. For the discharge current density of $\text{1000}\text{mA}\text{/}\text{g}$, the high rate dischargeability (HRD) of the alloy electrodes increases from 55.8% (x=0.0) to 72.3% (x=0.4) and then decreases to 70.0% (x=0.5). Moreover, according to the electrochemical impedance spectroscopy, linear polarization and anodic polarization measurements, the exchange current density I₀ and the limiting current density I_L of the alloy electrodes also all increase first and then decrease with increasing Mn content in alloys.     

Oxidation resistance of Ni/La0.7Sr0.3AlO3−δ catalyst for steam reforming of model aromatic hydrocarbon

Oxidative resistance of Ni catalysts supported on various oxides La_0.7Sr_0.3AlO_3−δ, LaAlO₃, and α-Al₂O₃ were investigated for hydrogen production by steam reforming of model aromatic hydrocarbons. Ni/α-Al₂O₃ lost its steam reforming activity by oxidation treatment. In contrast, Ni/La_0.7Sr_0.3AlO_3−δ and Ni/LaAlO₃ catalysts showed steam reforming activity even after the oxidation treatment. The XANES (X-ray absorption near-edge structure) spectra at Ni K-edge for Ni/La_0.7Sr_0.3AlO_3−δ and Ni/α-Al₂O₃ after oxidation treatment revealed that the supported Ni on La_0.7Sr_0.3AlO_3−δ and α-Al₂O₃ were oxidized completely. Although the mean particle size of Ni on Ni/α-Al₂O₃ increased by oxidation treatment or reduction treatment, Ni particles on Ni/La_0.7Sr_0.3AlO_3−δ retained the fine structure after oxidation treatment or reduction treatment. Moreover, TPR (temperature programmed reduction) and XPS (X-ray photoelectron spectroscopy) measurements for elucidating the reducibility of Ni/La_0.7Sr_0.3AlO_3−δ showed that the supported Ni on La_0.7Sr_0.3AlO_3−δ was easily reduced even after the oxidation treatment.     

Metal-supported solid oxide fuel cells with in-situ sintered (Bi2O3)0.7(Er2O3)0.3–Ag composite cathode

Metal-supported solid oxide fuel cells (SOFCs) containing porous 430L stainless steel support, Ni-YSZ anode and YSZ electrolyte were fabricated by tape casting, laminating and co-firing in a reduced atmosphere. (Bi₂O₃)_0.7(Er₂O₃)_0.3–Ag composite cathode was applied by screen printing and in-situ sintering. The polarization resistances of the composite cathode were 1.18, 0.48, 0.18, 0.09 Ω cm² at 600, 650, 700 and 750 °C, respectively. A promissing maximum power density of 568 mW cm⁻² at 750 °C was obtained of the single cell. Short-term stability was measured as well.     

Electrochemical behaviors of Y-doped La0.7Sr0.3CrO3−δ anode in sulfur-containing fuel SOFC

Fuel gas containing sulfur to feed solid oxide fuel cell is a challenge for extending the application of SOFC. Yttrium doped into La_xSr_1−xCrO₃ as potential anode tolerant to H₂S was investigated by XRD, XPS and electrochemical impedance spectra (EIS). Good sinter characteristic for (La,Y)_0.7Sr_0.3CrO_3−δ (LYSC) observed by SEM contributes to the low ohmic loss (high conductivity) in SOFC fueled by H₂(3%)–H₂S(1%). Maximum power density of 20 mW/cm² and open circuit voltage of 0.95 V for SOFC with LYSC can be obtained at 700 °C. The results by EIS indicate charge transfer loss in polarization resistance dominates in the total resistance, especially lower than 650 °C. Compared to ohmic loss, polarization resistance in LYSC is still the main cause to hinder the improvement of SOFC performance. Thus, LYSC with doped non-variant valence Y maintains good sulfur tolerance determined by XPS without improved electro-catalytic activity as EIS suggest.     

0.7MW中心回燃锅炉低氮燃烧改造

北京某酒店有2台0.7MW中心回燃式燃气锅炉,NO_x的原排放浓度约为110mg/m~3(标态),采用扩散式低氮燃烧器+烟气再循环技术的改造技术,成功将NO_x的排放指标在锅炉负荷范围内降低至30mg/m~3(标态),锅炉运行安全稳定。通过介绍中心回燃锅炉的特点及低氮改造的技术难点,提供了一种中心回燃式燃气锅炉低氮改造的技术路线和方法。     

Nanostructured GDC-impregnated La0.7Ca0.3CrO3−δ symmetrical electrodes for solid oxide fuel cells operating on hydrogen and city gas

Nanostructured Gd_0.1Ce_0.9O_1.95 (GDC)-impregnated La_0.7Ca_0.3CrO_3−δ (LCC) composites were investigated as symmetrical electrodes for La_0.9Sr_0.1Ga_0.8Mg_0.2O_3−δ (LSGM)-supported solid oxide fuel cells (SOFCs) without using interlayer at anode/electrolyte interface. The impregnation of aqueous Gd_0.1Ce_0.9(NO₃)_x solution into the porous LCC electrode backbones was found to form nanosized GDC particles on LCC surfaces after calcining at 850 °C for 30 min. The optimized performance of electrodes for SOFCs had been achieved through the impregnation cycles of 3-7 times. The introduction of the ion conducting phase GDC in nanometer significantly enhanced the symmetrical electrode performance. The symmetrical cell with the impregnation of five times displayed the best performance and the maximum power densities were 521 mW cm⁻² and 638 mW cm⁻² at 850 °C and 900 °C with dry H₂ as fuel, respectively. Using commercial city gas containing H₂S as fuel, the maximum power densities of the cell reached 362 mW cm⁻² and 491 mW cm⁻² at 850 °C and 900 °C, respectively. The microstructure, valence state of Ce element and electrochemical stability of the nanostructured GDC-impregnated LCC composites were also discussed.